Amazon seems to be selling a lot of its newest Kindle Fire tablets. But it would like to sell many more. So here’s Jeff Bezos’s newest pitch: Buy a Kindle Fire HDX tablet today, and we’ll give you nine months to finish paying for it. Amazon started pushing its installment plan program this weekend, by splashing the offer on its home page. The basics: It is letting customers pay for its $229 Kindle Fire HDX seven-inch tablet, or its $379 8.9-inch version, in four-part installment plans. Customers shell out 25 percent of the purchase price — plus tax and shipping charges – when they buy the gadget, and then spread out the remaining three payments in 90-day increments. There aren’t a lot of catches with the offer — for instance, Amazon isn’t adding any interest charges to its installment plan. But there is one interesting twist spelled out in the relatively fine print: If you don’t cough up the rest of the money, Amazon may semi-brick your tablet.